Butterfly check valve is an important fluid control device, which is mainly used to prevent the backflow of the medium and ensure the normal operation of the pipeline system. The following is a detailed introduction of the butterfly check valve: 

 1. Definitions and aliases 

 Butterfly check valve, also known as butterfly check valve and double-dip check valve, is a valve that automatically opens and closes the disc by relying on the flow of the medium itself. It also has aliases such as check valve, one-way valve, backflow valve, back pressure valve, etc. 

 2. Working principle 

 The working principle of the butterfly check valve is relatively simple. When the medium flows in a normal direction, the medium pressure pushes the valve disc to open, so that the medium passes smoothly; when the medium flows backwards, the disc automatically closes under the action of medium pressure and self-weight, cutting off the flow of the medium, so as to prevent the backflow of the medium. 

 3. Structural characteristics 

 Disc design: The disc of the butterfly check valve is disk-shaped and can be opened and closed by rotating around the axis. The valve disc can be designed as single-lap, double-lap or multi-lap to meet the needs of pipelines of different calibers. 

 Sealing performance: The sealing surface of the butterfly check valve can adopt body surfacing wear-resistant materials or lining rubber to improve sealing performance and service life. 

 Connection method: The butterfly check valve is often connected with a clip, that is, the valve body is directly sandwiched between the two flanges, which is easy and fast to install. 

 Fluid resistance: Due to the streamlined design of the inner channel of the valve, the fluid resistance of the butterfly check valve is relatively small, which is suitable for large-caliber occasions with low flow rate and irregular flow. 

 4. Scope of application 

 Butterfly check valves are widely used in industrial pipeline systems, especially when it is necessary to prevent the backflow of the medium. It is suitable for a variety of fluid media and temperature conditions, but it is necessary to pay attention to its working pressure and temperature range to meet the actual demand. 

 5. Installation and maintenance 

 Installation position: The butterfly check valve is generally installed on the horizontal pipe, but can also be installed on the vertical or inclined pipe according to actual needs. When installing, it should be noted that the flow direction of the medium is consistent with the direction of the valve body arrow. 

 Maintenance: Regularly check the sealing performance and opening and closing flexibility of the butterfly check valve, and clean up the dirt and impurities inside the valve in time to ensure its normal operation. 

 6. Advantages and disadvantages 

 Advantages: simple structure, easy to manufacture and maintain. It has a wide range of applications and can be used in a variety of fluid media and temperature conditions. Quick opening and closing, good sealing performance. 

 Disadvantages: Because the disc needs to rotate at a large angle during the opening and closing process, a certain noise may be generated. The requirements for the installation position are high, and it is necessary to ensure that the disc can rotate smoothly.